Bump codecov/codecov-action from 3 to 4 (#169)

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Nathan Zimmerberg <[email protected]>

Author: dependabot[bot]

.github/workflows/CI.yml

@@ -36,8 +36,9 @@ jobs:
       - uses: julia-actions/julia-buildpkg@v1
       - uses: julia-actions/julia-runtest@v1
       - uses: julia-actions/julia-processcoverage@v1
-      - uses: codecov/codecov-action@v3
+      - uses: codecov/codecov-action@v4
         with:
+          token: ${{ secrets.CODECOV_TOKEN }}
           files: lcov.info
   docs:
     name: Documentation